1. Field of the Invention
The present invention relates to a breaker device, in particular to a lever type breaker device.
2. Description of the Prior Art
A prior art lever type breaker device is constructed such that a lever is provided in a casing that has a pair of electrodes. The electrodes are engaged and disengaged by the rotation of the lever. Some prior art breaker devices of this type are provided with a locking mechanism for locking the lever in a specified rotational position. An unlock portion for unlocking the locking mechanism is provided in a position that can be seen by an operator, e.g. on a front surface of casing.
With the above construction, although the operator can easily find the unlock portion, unlocking may be effected inadvertently by a tool or the like striking against the unlock portion during an operation. On the other hand, if the unlock portion is provided in a position where a tool or the like is unlikely to strike it, then performance of an unlocking operation becomes difficult, thereby causing a lower work efficiency.
A switch member for switching the electrical connection of a pair of electrodes is provided in a casing of a known breaker device. A locking mechanism is provided between the switch member and the casing of this prior art device to lock the switch member in an ON state and an OFF state in the same manner to hold the respective states. Thus this known breaker device is capable of holding an operable member for switching the electrical connection of a pair of electrodes in a specified state.
However, as is illustrated next, it is sometime desirable to differ a lock holding force in the ON state and in the OFF state of the breaker device depending upon the use of the breaker device.
For example, in an electric automotive vehicle in which a breaker device for switching a main power source is provided in a trunk, the lock holding force in the ON state needs to be increased to prevent an erroneous operation caused by the contact of a baggage or the like during the driving. On the other hand, the lock holding force in the OFF state is desired to be lower than the lock holding force in the ON state so as to efficiently conduct a repair and/or inspection.
Further, in breaker devices that are enclosed by a cover to prevent an erroneous operation caused by a baggage or the like, it is preferable to have a smaller lock holding force in the ON state to facilitate unlocking with the cover detached. On the other hand, the lock holding force in the OFF state needs to be larger than the lock holding force in the ON state in order to prevent an erroneous operation caused by the contact of a tool or the like.
In view of the above problem, an object of the present invention is to provide a breaker device in which a lever can be locked in a specified position with an improved reliability and particularly unlocking can be easily effected.